device
Specifies the device whose control is to be interrogated
or modified.

controlType
Specifies the type of control to be interrogated or
changed.

control
Specifies the address of an XDeviceControl structure
that contains the new values for the Device.

DESCRIPTION

These requests
are provided to manipulate those input devices
that support device control. A BadMatch error will be
generated
if the requested device does not support any device
controls.

Valid device
control types that can be used with these requests
include the following:

DEVICE_RESOLUTION
Queries or changes the resolution of
valuators on input devices.

The
XGetDeviceControl request returns a pointer to an
XDeviceControl structure.

XGetDeviceControl
can generate a BadDevice or BadMatch error.

The
XChangeDeviceControl request modifies the values of one
control on the specified device. The control is identified
by
the id field of the XDeviceControl structure that is passed
with the request.

XChangeDeviceControl
can generate a BadDevice, BadMatch, or
BadValue error..SH STRUCTURES Each control is described by a
structure specific to that control. These structures are
defined in the file XInput.h.

XDeviceControl
is a generic structure that contains two fields
that are at the beginning of each class of control:

typedef struct
{
XID class;
int length;
} XDeviceControl;

The
XDeviceResolutionState structure defines the information
that is returned for device resolution for devices with
valuators.

DIAGNOSTICS

BadDevice
An invalid device was specified. The specified device
does not exist or has not been opened by this client via
XOpenInputDevice. This error may also occur if some
other client has caused the specified device to become
the X keyboard or X pointer device via the
XChangeKeyboardDevice or XChangePointerDevice requests.

BadMatch
This error may occur if an XGetDeviceControl request was
made specifying a device that has no controls or an
XChangeDeviceControl request was made with an
XDeviceControl structure that contains an invalid Device
type. It may also occur if an invalid combination of
mask bits is specified ( DvKey but no DvAutoRepeatMode
for keyboard Devices), or if an invalid KeySym is
specified for a string Device.

BadValue
Some numeric value falls outside the range of values
accepted by the XChangeDeviceControl request. Unless a
specific range is specified for an argument, the full
range defined by the argument´s type is accepted. Any
argument defined as a set of alternatives can generate
this error.